Genome-wide identification and expression analysis of the UGT gene family in honeysuckle

The UGT gene family plays critical roles in regulating plant growth, development, stress responses, and secondary metabolite synthesis. Although UGT proteins have been studied in numerous plant species, research on the UGT family in honeysuckle (Lonicera japonica Thunb.) remains limited.

In this study, a comprehensive genome-wide analysis of the UGT gene family was performed in honeysuckle. A total of 224 unique LjUGT genes were identified and classified into 21 distinct subfamilies (T71-T92 without T77) based on the phylogenetic analysis. These genes were unevenly distributed on the 9 chromosomes. Eighteen segmental duplication events and 61 tandem duplications were identified, of which only 3 were positive selection. Integrated analysis of promoter cis-acting elements, transcription factors, targeted miRNAs, and interacting proteins suggested that the expression and function of the LjUGT genes may be regulated by transcription factors and proteins through binding to the various binding sites and cis-acting elements, thereby putatively participating in diverse biological processes, including hormone signaling, stress response, and metabolism. The expression pattern analysis of LjUGTs in different tissues and under stress conditions indicated that Lj2A1135G32, Lj5A236T61, Lj6A350T83, and Lj7A737T47 emerged as candidate genes potentially associated with development, 46 genes showed expression changes under all 6 abiotic stresses, suggesting broad stress responsiveness. Additionally, there 7 genes were identified as candidate hub genes that may correlate with the low temperature stress tolerance in honeysuckle according to the WGCNA results, and further verification by qRT-PCR confirmed that Lj4A99G61 and Lj9A591T82 can be regarded as key candidate genes for in-depth research.

This study systematically identified 224 LjUGT genes in honeysuckle for the first time and characterized their physicochemical properties, phylogenetic relationship, and expression patterns. These findings provide a foundational resource for hypothesis-driven investigations into the functions and action mechanisms of LjUGTs.